How do you solve log x + log 3 = log 21?

1 Answer
Dec 18, 2015

color(white)(xx)=>x=7

Explanation:

color(white)(xx)logx+log3=log21

The sum of the logarithms is the logarithm of a product of the numbers being added:

color(white)(xx)color(red)(log(3x))=log21
=>color(red)(1/3xx)3x=color(red)(1/3xx)21
=>x=7